Utility of fine-needle aspiration in the diagnosis of panniculitis

Abstract

This is a retrospective reassessment of the most important cytopathologic features of 23 FNA smears with a cytologic diagnosis of panniculitis (PN). Patients were sent by clinicians. Clinical diagnoses were as follows: 16 suspicious of PN; three cutaneous metastases of an extracutaneous primary neoplasm; four with no clinical diagnosis. Thirteen cases were subsequently submitted to histopathologic study. The following cytoarchitectural patterns were found to be very useful for the cytologic diagnosis of PN: adipocytes intermingled with foamy histiocytes, donut-like granulomas, aggregates of adipocytes intermingled with plump histiocytes, a granular basophilic background forming a lattice-like pattern, and well-formed granulomas with or without multinucleated giant cells. Inflammatory cells could be seen combined with any of these cytoarchitectural patterns. FNA does not pretend to replace excisional biopsy as the diagnostic procedure for these entities but it is a very useful diagnostic tool in certain cases: for confirming the recurrence of PN previously diagnosed by histology, for evaluating the onset of subcutaneous nodules in patients with a non-cutaneous malignant primary neoplasm, for evaluating cutaneous nodules with no clinical suspicion, and for confirming a clinical diagnosis of PN and differentiating it from other entities that mimic PN clinically.